Diastero- and enantioselective intramolecular carbometalation reaction

Unger, Rozalia; Cohen, Theodore; Marek, Ilan

doi:10.1016/j.tet.2010.04.038

Cited by 14 publications

(2 citation statements)

References 95 publications

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“…Thus, Zn- 1 was shown to be partially configurationally labile from −20 °C in THF. The striking difference in behavior of Zn- 1 in comparison to that of its 3-alkyl-substituted analogues, which are reported to be configurationally stable up to 40 °C, ,,,,, remains unexplained.…”

Section: Resultsmentioning

confidence: 99%

Metallotropic Equilibrium and Configurational Stability of 3-Chloro-1-(trimethylsilyl)propargyl and -allenyl Metals: Comparative Study among Lithium, Titanium, and Zinc

et al. 2012

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A comparative study of the metallotropic equilibrium between 1-chloro-3-(trimethylsilyl)propargyl and -allenyl metals was undertaken by means of lithio-, titano-, and zinco-carbenoids. The lithium and zinc species were shown to react mainly in their allenic metallotropic forms, whereas the titanium species proved to react in both its propargylic and allenic forms. The configurational stability of these organometallics was next examined using a modification of the Hoffmann test. In each case, the organometallic was reacted with a chiral enantiopure electrophile. A comparison of the diastereomeric ratios obtained at low and high conversion rates of the reagent allows assessment of its configurational stability. The lithium species thus exhibited a configurational lability at −125 °C in Trapp mixture on the time scale of its reaction with (+)-camphor, while the titanium analogue proved to be configurationally stable at −40 °C in THF/Et 2 O on the time scale defined by its reaction with (S)-N-tritylprolinal. In the context of its reaction with the same electrophile, the zinc bromide species was proven to be partially labile from −80 °C in THF and its dynamic kinetic resolution was investigated.

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Section: Resultsmentioning

confidence: 99%

Metallotropic Equilibrium and Configurational Stability of 3-Chloro-1-(trimethylsilyl)propargyl and -allenyl Metals: Comparative Study among Lithium, Titanium, and Zinc

et al. 2012

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“… 1 Because of the release of ring strain, the addition on cyclopropenes represents a particular but successful case providing a new entry to a large variety of polysubstituted enantioenriched cyclopropanes. 2 In this context, and since the pioneering work of Lautens, 3 Fox, 4 and Nakamura, 5 the direct functionalization of achiral, unsaturated, 6 three-membered carbocycles have attracted much attention. 7 We and others have reported the catalytic enantioselective copper-, rhodium-, and lanthanide-catalyzed addition of sp 3 - and sp 2 -hydridized alkyl groups 8 − 10 as well as the addition of heteroelements 10a , 11 with excellent diastereo- and enantioselectivities ( Scheme 1 a).…”

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confidence: 99%